Let us go back to the type materials to investigate the cranial differences among the Meriones species (Rodentia, Gerbillinae)

The genus Meriones Illiger, 1811 comprises species that are mainly desert or semi-desert inhabitants in the Palearctic region. These species are usually distinguished from each other by some external and cranial characters, yet they show a considerable level of intra-specific variation. Studies demonstrated that their taxonomy is complex, and that they show a considerable level of morphological plasticity. This study mainly deals with such taxonomical issues in jirds belonging to the genus Meriones, and provides a contribution to their conservation status. To explore cranial shape and size differences among Meriones species, morphological variables of type specimens of ten valid Meriones species, as well as of their synonyms were investigated. These include Meriones libycus, M. crassus, M. persicus, M. tristrami, M. meridianus, M. hurrianae, M. rex, M. shawii, M. sacramenti, and M. arimalius. To obtain the geometry of the biological forms, 2D-landmark data was acquisitioned, and analysed using geometric morphometric techniques. Multivariate analyses on the shape data of ventral, dorsal, and lateral views showed that, although some species reveal an overlap in morpho-space, in some views they are morphologically distinct. A cluster analyses demonstrates the existence of at least two major groups. Although, it is possible to discriminate some Meriones species based on the relative bulla' size, the results support the hypothesis that this criterion is not applicable to all of them. Size analyses demonstrated that the inter-landmarks distances representing the length of the tooth row and the opening of suprameatal triangle are significantly different between some jird species, and hence should be considered as a distinctive trait in the identification keys on jirds. Conclusively, only a thorough systematic revision of the genus Meriones, considering zoogeographic and ecological data, may complete the puzzle of the taxonomy of these species.

Automated summary

This study focuses on the taxonomical issues of jirds belonging to the genus Meriones and their conservation status. By investigating the morphological variables of ten valid Meriones species, it was found that they exhibit differences in cranial shape and size. Some species show overlap in morpho-space, yet they are morphologically distinct in certain views. The study also identifies the existence of at least two major groups among the species.